There are many paint systems or applications which can render brush strokes on electrical documents in computer graphics systems. Brush strokes are drawn as a cursor is moved by a cursor moving device such as a mouse or a pen drawn over a pen tablet.
In many systems, a brush dab is comprised with a single nib. The size and shape of the brush nib may be changed by a user to render different brush strokes. However, in many systems, once a particular size and shape of the brush nib are selected, they are unchanged along a brush stroke.
In some systems, a nib shape is varied during a brush stroke. U.S. Pat. No. 5,155,813 issued on Oct. 13, 1992 to Donoghue et al discloses a computer apparatus for brush styled writing. A pen tablet is sampled to generate smooth brush strokes in real time to facilitate accurate calligraphy. U.S. Pat. No. 5,239,292 issued on Aug. 24, 1993 to Willan discloses how positional input from a graphics tablet is used to determine the position and some characteristics including nib shapes. However, those systems render only a single nib for a brush stroke.
Other paint systems can draw multiple nibs while a mouse is being moved. However, the positions of the multiple nibs are either fixed or simulated random. In impressionist clone systems, multiple nibs are provided at fixed positions. U.S. Pat. No. 5,347,620 issued on Sep. 13, 1994 to Zimmer refers to multiple dabs being rendered for each brush position. The position of the extra strokes is randomly generated to achieve the effect of a bristled brush.
There are many systems to simulate calligraphy, but no system has been proposed to render a brush stroke having a unique painting effect using multiple nibs.
It is therefore desirable to provide a paint system which can render a brush stroke with multiple nibs whose movement is controllable to provide unique painting effects.